Such a shaft has two end parts and an electrically active central part with conductors, all produced by machining of a single piece.
The end parts are intended to be placed on two bearings and have an appropriate shape.
In the active central part which forms the rotor of the machine, grooves and deep notches are machined for the electrical conductors. These are coils which must be insulated and maintained in the notches by wedges. This constitutes a difference in construction between synchronous machines and asynchronous machines, in which the conductors are generally conductive bars which do not require insulation or immobilization.
Thus, the costs and time periods for manufacturing shafts for the rotors of synchronous machines are currently high. They constitute a limitation in the manufacturing of electric machines.
It has appeared to be necessary to modify the structure of the rotor shafts of synchronous machines as well as their manufacturing process in order to significantly reduce cost and time of manufacturing.